HC-Pro as a tool to study silencing suppressor-mediated induction of disease symptoms in plants.

• Applicant: Privatdozent Dr. Michael Wassenegger
• Co-Applicants: Professor Dr. Mohammed Saleem Ali-Shtayeh; Dr. Raed Alkowni; Professor Dr. Victor Gaba, Ph.D.; Amit Gal-On
• Subject Area: Plant Breeding and Plant Pathology
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 34632154

It is important to understand the mechanisms of symptom development in response to virus infection to design new strategies to produce virus resistant plants. In general, symptoms induced by potyviruses are based on the cellular effects of one of their proteins, the helper-component proteinase (HC-Pro). In plants, the HC-Pro interferes with small RNA metabolism and function, and such interference is associated with anomalous plant development. The central region in the HC-Pro is associated with suppressor activity and RNA binding. A mutation within a highly conserved amino acid (FRNK) motif of the zucchini yellow mosaic virus (ZYMV) HC-Pro dramatically changes the severe wild type strain to an asymptomatic strain, but does not affect its accumulation in squash plants and suppressor activity is maintained. The ability of this mutation to uncouple symptoms from virus accumulation creates a unique opportunity to study the etiology of symptoms. In other potyviridae such a mutation in the HC-Pro always resulted in loss of infectivity. Our goal is to determine how this and other mutations in this conserved ZYMV HC-Pro motif affect host responses to potyvirus infection in cucurbit plants. In particular, we will focus on the effect of HC-Pro on small RNA accumulation.

• DFG Programme: Research Grants
• International Connection: Israel, Palestine